FR2936837A1 - Storage reservoir for storing e.g. aqueous urea solution in diesel engine of heavy truck, has filling pipe and aeration tube formed as single piece by molding, where aeration tube sets maximum filling level of reservoir - Google Patents

Abstract

The reservoir (3) has an inner side communicated with atmosphere via a circular filling pipe or passage (1) and a circular aeration tube or passage (2). The filling pipe and the aeration tube are formed as a single piece by molding. The aeration tube sets a maximum filling level (6) of the reservoir. The filling pipe and the aeration tube are situated inside a unique envelope or tube having a cylindrical section.

Description

Integration of the aeration tube on the filling pipe of an exhaust gas pollution control fluid tank Vehicle and heavy vehicle emission legislation provides inter alia for a reduction of NOx emissions in the atmosphere. To achieve this objective is known the SCR (Selective Catalytic Reduction) process which allows the reduction of nitrogen oxides by injection of a reducing agent, generally ammonia, into the exhaust line. This ammonia can come from the decomposition by thermolysis of a solution of an ammonia precursor whose concentration can be that of the eutectic. Such an ammonia precursor is generally a urea solution. It should be noted that the abovementioned legislation also provides for a reduction of particulate emissions, in particular by diesel engines, so that particle filters have been developed. In order to facilitate thermal regeneration of these, specific additives have also been developed. Refueling has therefore become a necessity in diesel vehicles equipped with an exhaust gas (especially diesel engines) or additive (such as urea or additives to reduce particle combustion temperature of a particulate filter (Fα additive) for example. By the term urea is meant any solution, generally aqueous, containing urea. The invention gives good results with eutectic solutions water / urea for which there is a quality standard: for example, according to DIN 70070, in the case of the solution of AdBlue ° (commercial solution of urea), the urea content is between 31.8% and 33.2% (by weight) (ie 32.5 +/- 0.7% by weight) from which a quantity of available ammonia of between 18.0% and 18.8% . The invention can also be applied to urea / ammonium formate mixtures in aqueous solution also and sold under the brand name DenoxiumTM and one of the compositions (Denoxium-30) contains an equivalent amount of ammonia to that of the aqueous solution. Adblue A. These have the advantage of freezing only from -30 ° C (relative to -11 ° C), but have the disadvantages of corrosion problems related to the possible release of acid 2936837 -2 formic and a less available market (while urea is widely used and readily available even in areas such as agriculture). The present invention is particularly interesting in the context of water / urea eutectic solutions.

By Fα additive is generally meant a composition, in solution in a hydrocarbon solvent, of a low temperature combustion catalyst of carbonaceous solid particles produced by the incomplete combustion of a heavy hydrocarbon in a spontaneous ignition engine. By heavy hydrocarbon is meant a liquid or pasty ordinary temperature fuel whose molecules comprise more than 9 carbon atoms. An example of such a heavy hydrocarbon is a petroleum cut called gasoil, usable in diesel type engines. Examples of suitable liquid additives are the iron and cerium salts in hydrocarbon solution. In order to be able to fill an additive tank appropriately, it is necessary to find a method of filling and venting to achieve a certain fluid filling height defined from the bottom of the tank. The cost, packaging and risk of failure of this system must also be taken into account. In the past, this problem was solved by using an external vent tube. One end of the aeration tube was attached to the top of the filler pipe. The other end of the aeration tube was attached to a filling vent. The air vent of the infill was designed at a specific height relative to the upper sidewalk on the tank. This height is also specific with respect to the bottom of the tank and corresponds to the essential dimension making it possible to control the fluid filling height. With this solution, as the tank fills, the air vent of the fill leaves a clear path to allow air to escape into the atmosphere. Once the filling height is reached, the ventilation opening of the filling no longer allows the tank to aerate, which creates inside a surplus fluid in the filling pipe. This phenomenon signals to the person performing the filling that it must stop and it also keeps the free dome that is required for the vapors inside the tank. The prior art filling process provided a solution that was not optimized in terms of cost, packaging and strength. The solution according to the prior art required the assembly of several pieces. Due to the nature of the assembly of the pieces, several areas of potential failures were observed. As there were two hoses, possible packaging problems arose and a risk of entanglement during installation. Finally, the solution according to the prior art was not optimized in terms of cost because requiring several parts, which induces a cost of assembly. For this purpose, the present invention relates to a tank for the storage of an exhaust gas cleaning additive (in particular diesel engine) comprising a filling pipe molded in one piece with a ventilation tube which is also used to set the maximum filling height. The integrated tube of the present invention decreases the cost and the risk of failure while providing conditioning facilities by integrating the filling passage, the aeration tube, and the filling vent into a single assembly. The functional difference between this solution and the past solution is that the aeration tube is integrated with the filler pipe. Functionally, this creates a set that is less likely to catch on something during production or installation. In addition, since the two passages are interconnected, the height between the aeration vent of the fill and the outlet of the fill pipe can be controlled. It has always been a common practice to separate the vent hole from the filling of the fill pipe. This practice derives from the design of fuel tanks in which the vent and fill limiting valve (FLVV) must often be positioned at a different location from the filler pipe. Therefore, the object of the invention has not become evident so far, although the above-mentioned specific cost, packaging and installation problems have been observed for a number of years. The solution according to the invention makes it possible in particular to obtain a product that can be packaged with more adjusted constraints and allows a greater complexity. In addition, this solution significantly reduces the risk of failure and has the potential to reduce costs. Unlike those of the prior art, this solution makes it possible to take advantage of increased flexibility with respect to the introduction and the conditioning of the filling pipe. It only requires one hole to route the pipe through the obstacles created by the inherent shape of the vehicle. The number of pieces is reduced compared to the prior art. This solution also incorporates two critical heights, a fill vent hole height and a fill pipe outlet height. This coupling increases the fluid height accuracy and eliminates the need for an additional welding operation. The solution according to the invention gives particularly good results with urea. The reservoir to which the present invention applies is preferably a plastic tank. It is shaped in a mold preferably by injection or extrusion blow molding, the latter method being preferred.

The present invention will be described in more detail with the aid of the accompanying drawings, which schematically illustrate 4 variants of the invention. Figure 1 illustrates an embodiment of the present invention. The interior of the fluid reservoir (3) communicates with the atmosphere via 2 separate passages via a pipe (7) having 2 fluid passages inside its diameter. The first passage (1) acts as a means for filling the fluid reservoir (3). The second passage (2) has 2 functions. The first of these functions consists of a means for allowing air to escape from the reservoir during filling via the filling passage (1). The second function of the passage (2) is to act as a means of terminating the filling process. The passage (2) terminates at a specific height (6) which corresponds to the desired maximum height (4) in the fluid reservoir (3). During a filling process, the tank (3) is able to provide aeration, until the fluid level (4) reaches the final height (6) specific to the ventilation passage. At this point, the opening at which the ventilation passage (2) ends (6), is covered with fluid, limiting the flow of air out of the tank (3) and pushing the fluid in the passage filling process (1), resulting in the end of the filling process either by the automatic shutdown via a filling device on the market, or simply relying on the impression of the person performing the filling that the reservoir 2936837 -5 may contain more fluid. In addition, the end point of the filling passage (5) is necessarily lower than the end point of the ventilation passage, regardless of its dimensions. In all embodiments, the pipe (7) and the reservoir (3) are arranged in a repeatable and reliable manner which sets the difference between the height of the top of the tank and the height of the lower ends of the passages. FIG. 1 shows an embodiment of the invention in which the ventilation passage (2) is situated concentrically on the outside of the filling passage (1). In other words: the ventilation tube and the filling pipe are concentric, the first being located outside the second.

Figure 2 shows another embodiment of the present invention wherein the two passages are circular and adjacent to each other and located within a single tube. Figure 3 shows another embodiment of the present invention wherein the vent passage (2) partially surrounds the fill passage. It has a half-moon cross section placed next to that of the filling passage, the assembly having a substantially circular section. FIG. 4 shows another embodiment in which a molded-blown pipe (7) has the same operating characteristics as the other embodiments but allows complex tube shapes to be created. In this embodiment, the two pipes were molded in one piece and are connected by a web of material, the height (5) of the filling passage being located at a specific distance below the height (6) of the ventilation passage. In all these embodiments, it is the repetitive and reliable arrangement of the pipe (7) with respect to the tank (3) which sets the difference between the height of the top of the tank and the height of the lower ends of the passages. The variants according to FIGS. 1 to 3 according to which the two tubes (aeration tube and filling tube) are situated inside a single envelope of substantially cylindrical section are preferred since they are simpler to achieve in practice. Indeed, it is sufficient to practice or to provide a single opening of substantially circular shape in the tank and to come attach (before or after molding the tank) the envelope.

Claims (3)

REVENDICATIONS1. Tank (3) for storing an exhaust gas cleaning additive of an engine comprising a filling pipe (1) integrally molded with a ventilation tube (2) which also serves to secure the maximum height (6) for filling the tank (3). 2. Tank (3) according to the preceding claim, characterized in that the aeration tube (2) and the filling pipe (1) are located within a single casing (7) of substantially cylindrical section. An exhaust gas cleaning system comprising a tank (3) 1 - according to claim 1 or 2.