DEVICE FOR THE FLUID SUPPLY OF A MOTOR VEHICLE

Abstract

The invention relates to a device for supplying liquid to a motor vehicle, which comprises: - a supply pump intended for pumping liquid from a liquid reservoir to a device for consuming this liquid, and - a filtration assembly (7) intended for filtering the liquid pumped by the supply pump. The filtration assembly (7) comprises a housing (8) in which a filtration member (9) is housed. The housing (8) forms a siphon connected to a suction inlet of the supply pump and includes an open end intended to open into the liquid contained in the liquid reservoir such that a path of this liquid in the siphon passes through a so-called high level, which, when the level of the liquid in the reservoir is below a predetermined threshold, is higher than the level of the liquid in the reservoir. The filtration member (9) comprises a filtration zone in the form of a pocket of filtration material extending vertically into the housing (8).

Description

LIQUID SUPPLY DEVICE FOR MOTOR VEHICLE Technical field of the invention

[0001] The invention relates to a liquid supply device for a motor vehicle. The invention also relates to a liquid reservoir for a motor vehicle comprising a liquid supply device according to the invention. Furthermore, the invention relates to a selective catalytic reduction device for a motor vehicle comprising a liquid reservoir according to the invention. Finally, the invention relates to a motor vehicle comprising a liquid reservoir according to the invention. Technical background

[0002] Liquid supply devices for vehicles are already known in the state of the art, which are used, for example, to inject an additive solution, in particular an ammonia precursor, into an exhaust line of an internal combustion engine, in order to carry out a selective catalytic reduction (also called by its acronym "SCR"). This selective catalytic reduction allows the reduction of nitrogen oxides (NO X) emitted by light and heavy goods vehicles equipped with an internal combustion engine, and therefore to reduce the pollution caused by these vehicles in order to comply with legislation on nitrogen oxide emissions. Selective catalytic reduction requires the use of a reducing agent, such as ammonia, at a precise concentration level and in a high quality. An ammonia precursor, such as urea, is generally used as an additive, which must therefore be precisely dosed and injected into the exhaust gas stream where it is hydrolyzed before converting nitrogen oxides (NO X ) into nitrogen (N2) and water (H2O). To do this, it is necessary to equip the vehicles with a tank containing the additive solution, as well as a device for dosing and injecting the desired quantity of additive into the exhaust line.

[0003] To avoid clogging the additive solution injector with impurities that may be present in the additive solution, it is known to filter the additive solution before its injection. In the prior art, a filtration member is arranged in the additive tank at the inlet of an additive solution feed pump allowing the additive solution to be pumped through the filtration member. By this arrangement, the additive solution is cleaned of its 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 against impurities present in the sucked additive solution.

[0004] After a certain period of use, impurities clog the filtration element. Clogging occurs more quickly when the impurities are numerous and large. This is particularly the case in highly polluted regions. When the level of clogging increases, the filtration capacity of the filtration element decreases and the filtration flow rate of the liquid through the filtration element becomes lower than the suction flow rate of the feed pump. As a result, the pump draws in all or part of the air, which causes losses in injection pressure of the liquid by the feed pump. This results in particular in difficulties in accurately dosing the injected additive and therefore a reduction in the efficiency of the selective catalytic reduction. The suction of air is all the more marked when the liquid level in the tank is low, thus exposing part of the filtration element to the air.

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

[0006] To this end, the subject of the invention is a liquid supply device for a motor vehicle, comprising:- a supply pump intended to pump liquid from a liquid reservoir to a device for consuming this liquid, and- a filtration assembly intended to filter the liquid pumped by the supply pump, the filtration assembly comprising a housing in which a filtration member is housed, in which the housing forms a siphon connected to a suction inlet of the supply pump and has an open end intended to open into the liquid contained in the liquid reservoir so that a path of this liquid in the siphon passes through a so-called high level, which, when the level of the liquid in the liquid reservoir is below a predetermined threshold, is higher than the level of the liquid in the liquid reservoir,characterized in that the filtration member comprises a filtration zone in the form of a pocket of filtration material extending vertically in the siphon-forming housing.,

[0007] Thus, when the feed pump is primed, it first sucks in the air present in the siphon-forming housing. This air suction creates a vacuum that raises the liquid level in the siphon and thus immerses the filtration member in the liquid. Consequently, at the end of the feed pump priming period, the filtration member is no longer in contact with air or, at the very least, the filtration member remains sufficiently submerged, even when the liquid level in the reservoir is below the predetermined threshold, to prevent the feed pump from sucking in air during its operation. In addition, since the immersion of the filtration member remains significant, even when the liquid level in the reservoir is low, the clogging effect of the filtration member, preventing the liquid from passing through it, is effectively limited.

[0008] The fact that the feed pump does not draw in air during operation thus prevents any instability or loss of pressure for the liquid injection carried out by the feed pump. This is particularly advantageous in cases where the liquid injected by the pump must be precisely metered, for example in the case where the liquid is an ammonia precursor intended to be injected into an exhaust line of an internal combustion engine in order to be used as an additive in a selective catalytic reduction reaction. The liquid feed device can be used with other liquids, for example with water or fuel.

[0009] It is understood that the liquid supply device according to the invention makes it possible to use large filtration members without risking a reduction in the injection pressure of the liquid by the supply pump since the filtration member is no longer in contact with air or, at the very least, the filtration member remains sufficiently submerged.

[0010] Furthermore, since the air present in the housing is expelled when the feed pump is primed, the level of clogging of the filtration member has little impact on the liquid filtration flow rate since the filtration member is not in contact with the air and can therefore only filter liquid. Thus, the liquid supply device according to the invention remains functional even when the filtration member is significantly clogged. The service life of the filtration member is thus increased, particularly in polluted regions where it tends to clog quickly.

[0011] The siphon housing, by its function, comprises a wall which is airtight and sealed against the liquid present in the tank. Thus, the filtering member is also protected from impurities which may be present in the liquid stored in the tank, thus increasing the service life of the filtering member. In particular, any oily residues which may be present in the liquid remain on the surface of the latter and are thus blocked by the siphon housing which prevents them from reaching the filtering member.

[0012] The term "impurity" means any foreign body in the liquid, for example, dust, soil, insects, tank chips, oils or solid particles. These foreign bodies may be floating, suspended or deposited at the bottom of the liquid tank.

[0013] The passage of the liquid through a so-called high level allows significant immersion of the filtration element in the liquid regardless of the filling level of the tank, within the limit of a minimum filling level.

[0014] The predetermined threshold corresponds, for example, to the liquid level in the reservoir for which at least part of the siphon-forming housing is no longer immersed. Preferably, the predetermined threshold corresponds to the liquid level in the siphon-forming housing for which the filtration member is no longer in contact with the air. It is thus understood that the filtration member remains sufficiently immersed in the liquid even when the liquid level in the reservoir is lower than the so-called high level inside the housing.

[0015] It is understood that a "pocket" comprises at least one wall delimiting a cavity open at one of its ends and closed at another of its ends forming a bottom of the pocket. According to the present invention, it is understood that the wall of the pocket is made of filtration material and that liquid can be filtered through this wall towards the interior of the pocket.

[0016] Since the filtration area in the form of a bag extends vertically in the housing, when the bag is completely immersed in liquid, for example after the pump has been primed and the air has been expelled from the housing, the available filtration area is optimized because all sides of the bag, over all their heights and widths, can be used to filter liquid that has not yet been filtered. It is thus possible to provide a particularly compact filtration assembly and therefore a liquid supply device that is also more compact.

[0017] The invention may also include one or more of the following optional features, taken alone or in combination.

[0018] The ratio V / h, where V is the volume of the filtration member and h the height of the filtration member, is between 400 mm² and 800 mm², preferably the ratio V / h is approximately equal to 600 mm². This ratio makes it possible to represent the filtering surface area of ​​the filtration member. Such filtration members have good filtration properties. The presence of the siphon-forming housing advantageously makes it possible to use such filtration members. Indeed, a filtration member having these dimensions has good filtration properties but, with the liquid supply devices of the prior art, generates a significant risk of loss of liquid injection pressure due to its large volume which can easily fill with air.The liquid supply device according to the invention makes it possible to expel air from the siphon-forming housing during priming, so that the use of such filtration members is possible without encountering this problem.

[0019] The liquid supply device further comprises a supply conduit extending vertically in the pocket between high and low points of the pocket, a first high end of the supply conduit being connected to the suction inlet of the supply pump and a second low end opening into the interior of the pocket. This is a simple means of facilitating the suction of the pump by allowing in particular the suction of liquid to take place close to the liquid level in the siphon-forming housing.

[0020] Preferably, the gap Δ between the second lower end of the feed duct and the bottom of the bag is between 10 and 90% of the height p of the bag, preferably, the gap Δ is approximately equal to 25% of the height p of the bag. This positioning of the second lower end of the feed duct makes it possible to optimize the suction of liquid by the feed pump through the feed duct whether at the time of priming the pump or of a subsequent suction.

[0021] The bag comprises at least two lateral filtration faces, each lateral filtration face being arranged opposite and at a distance from a wall of the housing. The surface area available for filtration is thus optimized. Indeed, it is understood that in this arrangement the lateral filtration faces are not in contact with the wall of the housing and can therefore be in direct contact with liquid that has not yet been filtered. Thus, the liquid can enter the bag not only through the bottom of the bag but also through the lateral filtration faces. The filtration area of ​​the filtration member is thus increased. Depending on the embodiments, the number of lateral faces may be different, for example between two and six.

[0022] The liquid supply device comprises means for heating the siphon-forming housing. Thus, it is possible to thaw the liquid that may have frozen in the siphon-forming housing in order to allow use of the liquid supply device. It should be noted that the heating means only have to heat the volume of liquid present in the siphon-forming housing. Since this volume is reduced, thawing the liquid present in it is therefore facilitated.

[0023] The feed pump is housed in a housing, with the filtration assembly arranged outside the housing and carried by this housing. The housing allows the various functional units of the liquid feed device to be grouped and connected together in a simple and efficient manner. This makes the manufacturing of the liquid feed device easier and allows for a compact liquid feed device.

[0024] Preferably, the liquid supply device further comprises means for removably attaching the filtration assembly to the housing. Maintenance of the liquid supply device is thus facilitated. Indeed, it is then easy to detach the filtration assembly from the housing in order, for example, to check the condition of the filtration member, in particular its level of clogging. It is then also easy to replace the filtration member when this is desirable. In particular, it is possible to replace the filtration member without having to carry out any manipulations on the rest of the liquid supply device, in particular on the supply pump. This reduces the risk of wear on the rest of the supply device, thereby increasing its service life.The removable fastening means may consist of any means known to those skilled in the art for simply and quickly attaching and detaching the filtration assembly from the housing. Preferably, these removable fastening means do not require the use of a tool to attach or detach the filtration assembly from the housing. For example, the removable fastening means are clip-on or screw-on fastening means for clipping or screwing the filtration assembly directly onto the housing. By screw-on fastening, we mean here the fact that the filtration assembly comprises a thread complementary to a thread carried by the housing so that the filtration assembly can be directly screwed onto the housing.Preferably, the threads of the filtration assembly and the housing form quarter-turn screw type fastening means, making it possible to attach and detach the filtration assembly from the housing by applying a quarter-turn rotation, i.e. 90°, to the filtration assembly. Attaching and removing the filtration assembly is thus particularly easy even when the space available for maneuvering is reduced.

[0025] The liquid is an aqueous solution, preferably an ammonia precursor. In the case where the liquid is an ammonia precursor, the liquid supply device can be advantageously used in the context of a selective catalytic reduction reaction for purifying exhaust gases from an internal combustion engine. According to another embodiment, the aqueous solution is water.

[0026] The invention also relates to a liquid tank for a motor vehicle equipped with a liquid supply device as described above. Thus, depending on the embodiments, the tank may be, for example, a tank for an aqueous solution such as water or urea, or a fuel tank. The tank may be made of any material. In the particular case of a urea solution tank, the material of the tank is preferably a material having good chemical resistance to urea. It is generally a plastic material. Polyolefins, in particular polyethylene and, more particularly, high-density polyethylene (HDPE), constitute preferred materials. This tank may be produced by any known transformation method. A known embodiment is the injection molding method. A preferred embodiment is the extrusion blow molding method.In this process, a parison – in one or more parts – is obtained by extrusion and then shaped by blowing into a mold. Molding the tank in one piece from a single-part parison gives good results.

[0027] The invention also relates to a selective catalytic reduction device intended to purify exhaust gases from an internal combustion engine of a motor vehicle, the selective catalytic reduction device comprising a liquid reservoir as described above in which the liquid is an ammonia precursor. The ammonia precursor is for example urea. The catalytic reduction device is thus improved since it is equipped with a liquid supply device according to the invention which makes it possible to reduce the risk of loss of injection pressure of the ammonia precursor over time. This is particularly advantageous since, as indicated above, it is important to precisely dose the ammonia precursor injected in the context of selective catalytic reduction and the loss of injection pressure of the ammonia precursor is detrimental to the precision of this dosage.

[0028] Finally, the invention also relates to a vehicle comprising a liquid reservoir as described above. Brief description of the figures

[0029] The invention will be better understood on reading the following description, given solely as a non-limiting example and with reference to the appended drawings in which:

[0030] is a schematic representation of a vehicle comprising a tank equipped with a liquid supply device according to the invention;

[0031] is a perspective view of the liquid supply device of the;

[0032] is a sectional view of a portion of the liquid supply device of the;

[0033] is a perspective view of a filtration assembly forming part of the liquid supply device of the;

[0034] is a front view of a portion of the filtration assembly of the;

[0035] is a longitudinal sectional view of the portion of the filtration assembly shown in ; and

[0036] is a schematic representation of the operation of the liquid supply device of the. Detailed description

[0037] Figures 1 to 7 show an embodiment of a liquid supply device 1 2 according to the invention. In the present case, the liquid supply device 1 2 is mounted on a lower wall of a liquid tank 3 which is itself mounted on a motor vehicle 4 ().

[0038] In the present case, the liquid is an ammonia precursor, such as urea. The liquid reservoir 3 and the liquid supply device 1 are thus part of a selective catalytic reduction device 18 intended to purify exhaust gases from an internal combustion engine (not shown) of the motor vehicle 4.

[0039] The material from which the liquid reservoir 3 is made is preferably a material having good chemical resistance to urea. This is generally a plastic material. Polyolefins, in particular polyethylene and, more particularly, high-density polyethylene (HDPE), are preferred materials. This reservoir can be made by any known processing method. A known method of implementation is the injection molding method. A preferred method of implementation is the extrusion-blow molding method. In this method, a parison – in one or more parts – is obtained by extrusion and then shaped by blowing in a mold. Molding the reservoir in one piece from a parison in one part gives good results.

[0040] The liquid 2 supply device 1 comprises in particular a housing 5, a supply pump 6 and a filtration assembly 7 (figures 2, 3, 4 and 7).

[0041] The housing 5 forms a support member for the various functional units of the liquid supply device 1 2. In the present case, the supply pump 6 is housed inside the housing 5 and the filtration assembly 7 is arranged outside the housing 5 and carried by this housing 5 (figures 2). More particularly, the liquid supply device 1 2 comprises removable fixing means (not shown) for fixing the filtration assembly to the housing 5. Preferably, these removable fixing means do not require the use of a tool to secure or detach the filtration assembly 7 and the housing 5. For example, the removable fixing means are clip-on or screw-on fixing means allowing the filtration assembly 7 to be clipped or screwed directly onto the housing 5.

[0042] The other functional units of the liquid supply device 1 2 are conventional and are not shown for the sake of clarity. The housing 5 can be made of any material having good chemical resistance to urea. For example, the housing 5 is made of thermoplastic material.

[0043] The feed pump 6 is intended to pump liquid from the liquid reservoir 3 to a device for consuming this liquid (not shown). In the present case, the liquid being an ammonia precursor, the device for consuming this liquid is a selective catalytic reduction reaction catalyst. It is understood that the liquid consumption device is different depending on the desired use of the liquid 2 feed device 1, and more particularly depending on the nature of the liquid 2 contained in the liquid reservoir 3. The feed pump 6 used is known in itself and will not be described in more detail here. It is understood that the feed pump 6 may in particular correspond to a feed pump 6 conventionally used for injecting ammonia precursor in the context of a selective catalytic reduction reaction in a motor vehicle 4.

[0044] The filtration assembly 7 is intended to filter the liquid 2 pumped by the feed pump 6 in order to ensure that the liquid 2 injected into the selective catalytic reduction reaction is substantially free of impurities. The filtration assembly 7 notably comprises a housing 8 in which a filtration member 9 is housed ().

[0045] The housing 8 has a generally parallelepiped shape with a first closed longitudinal end and a second longitudinal end, opposite the first longitudinal end, which is open. In the present case, the housing 8 is formed in two parts, a first part forming the main body 10 of the housing 8 and a second part forming a closing cover 11 intended to seal the first longitudinal end of the housing 8 in a sealed manner against air and liquid 2 present in the liquid reservoir 3. Alternatively, the housing 8 can be manufactured so that the body 10 and the cover 11 are made in one piece.

[0046] The housing 8 forms a siphon which is connected to a suction inlet 12 of the feed pump 6 at its first closed longitudinal end via a feed conduit 13. The second open longitudinal end of the siphon-forming housing 8 opens into the liquid 2 contained in the liquid 2 reservoir 3 so that a path of this liquid 2 in the siphon passes through a so-called high level, which, when the liquid level in the liquid reservoir 3 is below a predetermined threshold, is higher than the level of the liquid 2 in the liquid 2 reservoir 3 (see). For example, the predetermined threshold may be located substantially at the first open longitudinal end of the siphon-forming housing 8. Preferably, the predetermined threshold corresponds to the liquid level in the siphon-forming housing 8 for which the filtering member 9 is immersed in the liquid 2.

[0047] The filtering member 9 is made from a flexible filter mesh fixed to a rigid frame. The filter mesh is flexible and is for example wound over or under the rigid frame. Advantageously, the filter mesh and the rigid frame are made of thermoplastic material and are welded to each other. Alternatively, the flexible filter mesh is manufactured in one piece with the rigid frame (figures 5 and 6).

[0048] The filtration member 9 comprises a filtration zone which extends vertically in the housing 8 forming a siphon. In other words, the filtration member 9 is arranged vertically in the housing 8 which is also arranged vertically when it is mounted on the housing 5 (figures 2, 3 and 7). More particularly, the filtration zone of the filtration member 9 comprises a pocket 14 of filtration material formed by the filter mesh.

[0049] The pocket 14 comprises at least one wall delimiting a cavity open at one of its ends and closed at another of its ends forming a bottom of the pocket. In the present case, the opening of the pocket 14 allows the passage of the supply conduit 13. According to the present embodiment, the pocket 14 comprises two lateral filtration faces 19, 20, each lateral filtration face 19, 20 being arranged opposite and at a distance from a wall of the housing 8 (figures 3 and 7).

[0050] In this case, the ratio V / h, where V is the volume of the filtration member 9 and h the height of the filtration member 9, is between 400 mm 2 and 800 mm 2 , preferably the V / h ratio is approximately equal to 600 mm 2 . In the present embodiment, the filtration bag 14 has a height p of approximately 68 mm which is slightly less than the height h of the filtration member ().

[0051] The supply conduit 13 has a general shape of an inverted “L” and extends vertically in the pocket 14 between high and low points of the pocket 14. A first high end 15 of the supply conduit 13 is connected to the suction inlet 12 of the supply pump 6 and thus makes it possible to put the interior of the housing 8 forming a siphon and the suction inlet 12 of the supply pump 6 into fluid communication (Figures 3 and 7). A second low end 16 of the supply conduit 13 opens into the interior of the pocket 14 (Figures 5 and 6). Depending on the embodiments, the height at which the second low end 16 of the supply conduit 13 opens into the pocket 14 varies. In the present case and advantageously, the gap Δ between the second lower end 16 of the supply conduit 13 and the bottom of the pocket 14 is approximately 15.5 mm, which represents approximately 23% of the height p of the pocket 14 ().Advantageously, the gap Δ between the second lower end 16 of the supply conduit 13 and the bottom of the pocket 14 is between 10% and 90%, preferably the gap Δ is approximately equal to 25% of the height of the pocket.

[0052] The liquid supply device 1 further comprises means 17 for heating the housing 8 forming a siphon. In the present case, these heating means 17 are formed by a heating sheet partially covering the housing 8 forming a siphon. According to other embodiments, any heating means capable of being arranged inside a reservoir 3 of liquid 2 in order to heat the housing 8 forming a siphon can be used. For the sake of clarity, the heating means 17 are shown only on the.

[0053] An example of operation of the liquid supply device 1 2 according to the invention is described below with reference to the.

[0054] As previously indicated, the liquid 2 supply device 1 is implemented in the present case for a selective catalytic reduction reaction in order to inject liquid 2, here an ammonia precursor, into the exhaust gas flow of the motor vehicle 4 where it is hydrolyzed in order to convert nitrogen oxides (NO X ) into nitrogen (N2) and water (H2O).

[0055] Figure 7A represents the state of the liquid 2 supply device 1 before its use, that is to say before the supply pump 6 is started. Here, the level of liquid 2 in the liquid reservoir 3 is relatively low so that a significant portion of the filtration assembly 7, and in particular of the siphon-forming housing 8, is not immersed in the liquid 2. Air is present inside the siphon-forming housing 8.

[0056] When an injection of liquid 2 into the exhaust gas flow is desired, the feed pump 6 is activated. During a first priming step, the feed pump 6 sucks in, via its suction inlet 12 and along the feed duct 13, a mixture of air present in the siphon-forming housing 8 and liquid 2. The suction of the air creates a depression which causes an increase in the level of liquid 2 inside the siphon-forming housing 8 (figure 7B).

[0057] At the end of the priming period, all or a greater part of the air that was present inside the siphon-forming housing 8 has been sucked in by the feed pump 6 so that the siphon-forming housing 8 is filled with liquid 2 at least so as to completely or almost completely immerse the filtration member 9 (FIG. 7C). It can be seen that the level of liquid 2 in the siphon-forming housing 8 is here higher than the level of liquid 2 present in the liquid 2 reservoir 3. The filtration member 9 is then immersed in the liquid and is not in contact with air. At this stage, the feed pump 6 can therefore no longer, or practically no longer, suck in air. Thus, the risk of a loss of injection pressure of the liquid 2 is reduced or even zero. Furthermore, the immersion of the filtration member 9 after priming the pump is obtained regardless of the extent of the clogging of the filtration member 9.Thus, even with high clogging of the filtration member 9 it is possible to continue to use this filtration member 9 with a liquid supply device 1 2 according to the invention since the air having been expelled from the housing 8 forming a siphon, it can in any case no longer be sucked in by the supply pump 6 and cause a drop in injection pressure of the liquid 2.

[0058] The results of a test intended to measure the efficiency of the liquid 2 supply device 1 according to the invention are described below as a function of the clogging level of the filtration member 9. Thus, the filtration members 9 were tested for a clogging level, as a percentage of the height h of the filtration member 9, of 0% (control), 10%, 20%, 30%, 40% and 50%. To control the clogging level, this was achieved artificially by covering the filtration member 9 with an epoxy resin over a height corresponding to the desired percentage clogging level starting from the lower end of the filtration member 9.The effectiveness of the liquid 2 supply device 1 according to the invention was tested by measuring the quantity of aqueous solution, here urea, which can be injected using the filtration member 9 alone, as is the case in the prior art, or housed in a housing 8 forming a siphon of a filtration assembly 7 according to the invention. The results of the test are presented in Table 1.

[0059] Clogging levelVolume of urea to be injected (kg)Volume of urea injected with a liquid supply device of the prior art (kg)Volume of urea injected with a liquid supply device according to the invention (kg)0%5,0004,821Not applicable (NA)10%5,0004,5404,82420%5,0004,4594,84430%5,0003,6854,82140%5,0003,3434,81050%5,0003,2474,841

[0060] The volume of urea is measured in kilograms rather than liters to facilitate measurements. Alternatively, it would be possible to conduct this test by measuring the volume of urea in liters. According to this test, 5 kg of urea are to be injected by a liquid 2 supply device 1 comprising either a filtration member alone (case representing the prior art), or a filtration assembly 7 according to the invention in which the filtration member 9 is housed in a housing 8 forming a siphon.

[0061] The case where the clogging level is at 0% was tested only on the prior art liquid supply device in order to give a reference value. Thus, in the prior art, with a filtration member which is not clogged, generally because it is new, the volume of urea injected from 5 kg of urea is 4.821 kg.

[0062] In the case where the filtration member 9 is clogged to 10%, a reduction in the urea injected is observed for the liquid supply device of the prior art. The volume of urea injected is 4.540 kg instead of 4.821 kg when the filtration member 9 is not clogged, i.e. a loss of 0.281 kg of urea. It is noted that this reduction is not visible with the liquid supply device 1 2 according to the invention since 4.824 kg of urea were injected. Thus, a slight increase in the volume of urea injected is even observed compared to the control case (increase of 0.003 kg). At 10% clogging, the filtration capacities of the filtration assembly 7 according to the invention are therefore better than those of the prior art and make it possible to maintain a filtration level substantially equivalent to a filtration level obtained when the filtration member 9 is new.

[0063] In the case where the filtration member 9 is clogged by 20%, a decrease 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 filtration member 9 is not clogged, i.e. a loss of 0.362 kg of urea. Again, it is noted that this decrease is not visible with the liquid supply device 1 2 according to the invention since 4.844 kg of urea were injected. Thus, a slight increase in the volume of urea injected is still observed compared to the control case (increase of 0.023 kg). At 20% clogging, the filtration capacities of the filtration assembly 7 according to the invention are therefore better than those of the prior art and make it possible to maintain a filtration level substantially equivalent to a filtration level obtained when the filtration member 9 is new.

[0064] In the case where the filtration member 9 is clogged to 30%, a decrease 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 filtration member 9 is not clogged, i.e. a loss of 1.136 kg of urea. Again, it is noted that this decrease is not visible with the liquid supply device 1 2 according to the invention since 4.821 kg of urea have been injected, i.e. as much as with a new filtration member 9. At 30% clogging, the filtration capacities of the filtration assembly 7 according to the invention are therefore better than those of the prior art and make it possible to maintain a filtration level substantially equivalent to a filtration level obtained when the filtration member 9 is new.

[0065] In the case where the filtration member 9 is clogged to 40%, 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 filtration member 9 is not clogged, i.e. a loss of 1.478 kg of urea. It is noted that this reduction is not very significant with the liquid supply device 1 2 according to the invention since 4.810 kg of urea were injected, i.e. a loss of only 0.011 kg of urea. At 40% clogging, the filtration capacities of the filtration assembly 7 according to the invention are therefore better than those of the prior art and make it possible to maintain a filtration level substantially equivalent to a filtration level obtained when the filtration member 9 is new.

[0066] In the case where the filtration member 9 is 50% clogged, a decrease 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 filtration member 9 is not clogged, i.e. a loss of 1.574 kg of urea. Again, it is noted that this decrease is not present with the liquid supply device 1 2 according to the invention since 4.841 kg of urea were injected, i.e. an increase of 0.020 kg of urea compared to the control case. At 50% clogging, the filtration capacities of the filtration assembly 7 according to the invention are therefore better than those of the prior art and make it possible to maintain a filtration level substantially equivalent to a filtration level obtained when the filtration member 9 is new.

[0067] This test makes it possible to conclude on the filtration efficiency of a filtration member 9 over time, that is to say as it becomes clogged. The loss of filtration efficiency for the filtration members of the prior art corresponds in practice to an increased risk of loss of injection pressure during the use of the device 1 for supplying liquid 2. As indicated previously, this loss of injection pressure is disadvantageous, in particular in cases where the quantity of liquid 2 to be injected must be precisely metered, since it does not make it possible to obtain an acceptable level of precision with regard to the quantity of liquid 2 injected.Thus, this test shows that the use of a device 1 for supplying liquid 2 according to the invention makes it possible to preserve the filtration capacities of the filtration member 9 over time, even for significant clogging, and thus to reduce the risk of loss of injection pressure of the liquid 2 over time.

[0068] The invention is not limited to the embodiment presented and other embodiments will become apparent to those skilled in the art. List of references

[0069] 1: liquid supply device2: liquid3: tank4: motor vehicle5: housing6: supply pump7: filtration assembly8: housing9: filtration member10: housing body11: housing cover12: suction inlet of the supply pump13: supply duct14: pocket of the filtration member15: first upper end of the supply duct16: second lower end of the supply duct17: means for heating the housing forming a siphon18: selective catalytic reduction device19, 20: lateral filtration facesh: height of the filtration memberp: height of the filtration pocketΔ: distance between the second lower end of the supply duct and the bottom of the pocket

Claims

A liquid supply device (1) for a motor vehicle (4), comprising: - a supply pump (6) for pumping liquid (2) from a liquid reservoir (3) to a liquid consumption device (2), and - a filtration assembly (7) for filtering the liquid (2) pumped by the supply pump (6), the filtration assembly (7) comprising a housing (8) in which a filtration element (9) is housed, the housing (8) forming a siphon connected to a suction inlet (12) of the supply pump (6) and having an open end for opening into the liquid (2) contained in the liquid reservoir (3) such that a path of this liquid (2) in the siphon passes through a so-called high level, which, when the level of the liquid (2) in the liquid reservoir (3) is below a predetermined threshold, is higher than the level of the liquid (2) in the reservoir. (3) of liquid (2),characterized in that the filtration organ (9) comprises a filtration zone in the form of a pocket (14) of filtration material extending vertically into the housing (8) forming a siphon. Liquid supply device (1) (2) according to claim 1, wherein the ratio V / h, where V is the volume of the filtering element (9) and h the height of the filtering element (9), is between 400 mm² and 800 mm², preferably the ratio V / h is about 600 mm². Liquid supply device (1) according to claim 1 or 2, wherein the liquid supply device (1) (2) further comprises a supply conduit (13) extending vertically in the pouch (14) between high and low points of the pouch (14), a first high end (15) of the supply conduit (13) being connected to the suction inlet (10) of the supply pump (6) and a second low end (16) opening into the interior of the pouch (14). Liquid supply device (1) according to claim 3, wherein the gap (Δ) between the second lower 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 gap (Δ) is about 25% of the height (p) of the bag (14). Liquid supply device (1) (2) according to any one of the preceding claims, wherein the bag (14) comprises at least two lateral filtration faces (19, 20), each lateral filtration face being arranged opposite and at a distance from a wall of the housing (8). Liquid supply device (1) (2) according to any one of the preceding claims, comprising means (17) for heating the housing (8) forming a siphon. Liquid supply device (1) according to any one of the preceding claims, wherein the supply pump (6) is housed in a casing (5), the filtration assembly (7) being arranged outside the casing (5) and carried by this casing (5). Liquid supply device (1) according to claim 7, further comprising means for removable fixing of the filtration assembly (7) on the housing (5). Liquid supply device (1) according to any one of the preceding claims, wherein the liquid (2) is an aqueous solution, preferably an ammonia precursor. reservoir (1) of liquid (2) for motor vehicle (4), characterized in that it is equipped with a device (1) for supplying liquid (2) according to any one of the preceding claims. Selective catalytic reduction device (18) for purifying exhaust gases from an internal combustion engine of a motor vehicle, characterized in that it comprises a reservoir (3) of liquid (2) according to claim 10, in which the liquid (2) is an ammonia precursor. Motor vehicle (4) characterized in that it comprises a reservoir (3) of liquid (2) according to claim 10.