FR2948146A1 - Liquid reducing agent i.e. urea aqueous solution, dosing module, for internal combustion engine of e.g. tractor, has driving unit for actuating dosing installation, and sealably closed with respect to ring by sealing cap - Google Patents

Abstract

The module has cases (14, 16) surrounding a dosing installation (18), and a driving unit (36) for actuating the dosing installation. The dosing installation and the driving unit are separate assemblies and installed in the cases. A zone of the driving unit is positioned and/or blocked in the cases by an adaptive ring (42). The dosing installation is sealably connected to the cases. The driving unit is sealably closed with respect to the ring by a sealing cap (46).

Description

FIELD OF THE INVENTION The present invention relates to a dosing module for a liquid reducing agent, in particular an aqueous urea solution for injecting the reducing agent into the exhaust gas duct of a combustion engine. internal, - the dosing module comprising a housing surrounding a metering installation and a drive unit operating the metering installation. State of the art The emission limits laid down by the legislator for nitrogen oxides require the use of exhaust aftertreatment plants emitted by engines of motor vehicles, utilities or tourism. These plants provide, for example, a selective catalytic reduction (abbreviated SCR reduction) of the nitrogen oxides of the gross emissions of the internal combustion engine. For this, a liquid reducing agent (an aqueous urea solution) is injected into the engine exhaust gas duct on demand to allow the selective catalytic reduction of the nitrogen oxides in a SCR catalyst (catalytic converter). selective catalytic reduction). Urea is then decomposed into ammonia (NH3), which reacts with the nitrogen oxides (NOx) in the exhaust gases and transforms them into water (H2O) and nitrogen (N2) which are non-polluting. This exhaust gas cleaning process SCR is aware of the state of the art.

DE 10 2007 043 532 A1 discloses a dosing module for the aqueous solution of urea in an exhaust gas system of an internal combustion engine. This module includes a drive unit and a dosing system. A diaphragm separates the constructive unit from the drive unit and the dosing unit. The metering device and the actuating member transmitting an actuating force through the diaphragm to the metering device are separate components. The drive unit is fixed by a fixing member of the metering device via the housing by means of a screwed or glued connection. The seal against the inside of the dosing module and the

2 cooling of the dosing module, is not subject to any special conditions. OBJECT OF THE INVENTION The object of the present invention is to develop a dosing module of the type defined above so that the internal volume of the dosing module is practically unaffected by external influences. The dosing module must also be compact and its cost of implementation and assembly must be reduced. DESCRIPTION AND ADVANTAGES OF THE INVENTION To this end, the invention relates to a dosing installation of the type defined above, characterized in that - the dosing system and the drive unit are separate units, installed in the housing, - at least the area of the drive unit is positioned and / or locked in the housing by an adapter ring, and the dosing system is sealingly connected to the housing, - the The drive unit is further sealingly closed to the adapter ring by a sealing cap. The dosing module housing is a substantially cylindrical component and according to the invention, the housing is designed to receive the dosing system with the membrane and the drive unit to be housed in the housing. The side of the housing receiving the drive unit is closed by the adapter ring and the sealing lip allows the electrical connection of the electromagnets of the drive unit, the closure being made in a sealed manner with appropriate means . The opposite side of the housing is also sealed by appropriate means. This means that the dosing module is certainly formed of several assemblies separately-made assembly, but it then constitutes a closed unit hermetically. Thus, the safety of the operation of the do-wise module is ensured even if the dosing module is completely immersed in water. Such a situation may for example arise if the commercial vehicle (for example a tractor) is used in a

3 submerged rice field. In addition, there is generally better protection against dirt and splashing water. Advantageously, the metering device according to the invention and / or the adapter ring according to the invention are connected to the housing by welding and / or matting (crimping). These two modes of liai-son realize tight and integral bonds, because by matting (crimping-wise), one makes a connection by plastic deformation, by force and by the form between two pieces. The deformation of the edge of the piece is made so that the pieces are wedged one into the other in solidarity. Unlike the welding of parts made of metal and providing a connection by the material, by matting, one can also seem to different materials such as for example a plastic and metal. This allows for example to manufacture the adapter ring or the plastic housing. Alternatively, it is also possible to envisage a connection by the material, for example by brazing. It is also possible to connect the metering installation and / or the sealing cap by an engaged connection, in particular an interlocking connection cooperating with a safety ring to ensure connection with the housing. In the case of clipped connections, use is made of the elasticity of at least one of the materials, in general, the plastic material or the steel of the components to be joined to make the connection of the two parts. In the case of clipped connections, an assembly part deforms elastically and then clings into projecting parts ensuring the grip by a removable or integral connection to the other assembly part. The clipped connection can be made by external or internal grip with the parts projecting attachment. The fixing ring which surrounds the snap connection is in principle a fixing means avoiding its loss. This embodiment is particularly easy to assemble and allows a very fast assembly. It is also possible to connect the dosing system and / or the sealing cap by a crimping connection to the housing. The crimp connection consists of deforming the edge of round or oval metal pieces, using a crimping machine or manually working. The sheet is packed by this transformation. For

4, a crimping iron is used, that is a tool having a rounded edge. The crimped connection also guarantees the safety and sealing of the connection. It is also possible to connect the dosing system and / or the sealing cap by a self-hooking connection to the housing. In the case of the self-hooked connection, the crimping is produced by pressing a locking element for example in a groove. This also guarantees the safety and sealing of the connection. All the fixing possibilities have in common to make it possible to eliminate the elastomer sealing elements, undergoing wear and aging in a zone of reducing agent strongly-stressed thermally and chemically. The fixing possibilities themselves, undergo virtually no aging. This results in an economical and reliable device.

It is also advantageous that the metering device comprises as an integral component, a flange to be attached to the exhaust pipe. The dosing system is also integrated into the flange. This avoids the fastening part of the dosing system because the fastening function is ensured by the material of the flange, which eliminates any additional connection point between the dosing module housing and the dosing system. it should be sealed. This results in a compact construction dosing module and reduces manufacturing and assembly costs. It is furthermore advantageous to cool the dosing module with a coolant. For this purpose, the dosing module preferably comprises peripheral channels of coolant, in particular at the level of the flange and / or at the level of the sealing cap. This makes it possible to cool particularly the thermally highly stressed zone of the metering module in contact with the exhaust pipe. But it is also possible that the sealing cap has cooling channels to cool the drive unit. If the sealing cap reaches the flange, the coolant channels of the sealing cap allow cooling of the entire dosing module. This solution has the advantage that on the one hand the cooling water connections are remote from the sensitive zone of the flange, that is to say that they can be located at any location but preferably in the electrical connection area, in the opposite zone of the flange at the end of the sealing cap. On the other hand, the ambient temperature around the thermosensitive electromagnetic coil of the electromagnet may be limited to the temperature of the cooling water. This thus makes it possible to ensure a virtually cold contact of the electrical connection contacts. This cooling protects the dosing module against the influence of temperature in addition to the action of water and dirt. Drawings The present invention will be described hereinafter in more detail by means of exemplary embodiments shown in the accompanying drawings in which: - Figure 1 is a schematic longitudinal sectional view of a first embodiment of 2 is a schematic view in longitudinal section of a second embodiment of a dosing module; FIG. 3 is a diagrammatic view of the housing of the dosing valve of FIG. 1 showing a detail of another possibility of its attachment to the flange; FIG. 4 is a diagrammatic view of the housing of the do-wise valve of FIG. 1 showing the detail of another possibility of its attachment to the flange; FIG. FIG. 5 is a diagrammatic view of the sealing cap of FIGS. 1 or 2, in detail for a second embodiment, FIG. 6 is a diagrammatic view of a variant of the sealing cap of FIGS. Figures 1, 2 or 5, - the 7 is a diagrammatic detail view of a second possibility of fixing the sealing cap of FIG. 5; FIG. 8 is a diagrammatic view of a third possibility of fixing the sealing cap of FIG. FIG. 5 is a diagrammatic view in detail of a fourth possibility of fixing the sealing cap of FIG. 5.35.

Description of Embodiments of the Invention Figure 1 shows a metering module 10 for injecting a reducing agent into an unrepresented exhaust pipe of an internal combustion engine corresponding to a first embodiment. The dosing module 10 comprises a base 14 with a flange 12 which is transformed into a cylindrical casing 16. The flange 12, the base 14 and the casing 16 are made in one piece, preferably in stainless steel. The flange 12 has in its middle an opening receiving a metering installation. This installation is carried out in the form of a valve group 18 mounted in an adjusted manner and fastened together by a weld bead 19. Thus, the inside of the do-wise module 10 is at the same time sealed against to the outside. Alternatively, the valve group 18 may be attached by caulking, snapping, crimping, self-locking, or screwing. The flange 12 is attached to the exhaust gas pipe not shown with the screws 20. The valve assembly 18 includes a fastener to the housing 22 carrying a metering valve 24 with a valve member 26. The Valve member 26 cooperates in the direction of emission of the reducing agent with a valve seat 28. The base 14 further has a reducing agent inlet and a bore 32 for the passage of the cooling water. . The inlet 30 and all the components coming into contact with the reducing agent are made of stainless steel and / or aluminum to resist the reducing agent. On the opposite side to the direction of passage of the reducing agent, the valve unit 18 is delimited by a membrane 34. Next, there is the drive unit 36 actuating the check valve 24 by the Intermediate membrane 34. The drive unit 36 comprises an armature pin 38 biased by a spring, actuated by the electromagnet 40 being applied against the membrane 34. In the embodiment shown, the drive unit 36 is housed in the housing 16 from the side opposite to that of the flange 12. The drive unit 36 is fixed at its end opposite to that of the armature 38 by an adapter ring 42 and a weld bead to the drive unit 36 and a weld bead 44 to the housing 16. Other attachment possibilities exist as

7 for example those mentioned above. A sealing cap 46 is provided on the adapter ring 42. This sealing cap at the same time makes the electrical connection and the passage of the power supply. The sealing cap 46 could also include a cooling water connection (this is not shown in Figure 1). The sealing cap 46 is housed in the enlarged area 48 of the casing 16 by being fixed by matting or crimping 50. The sealing cap 46 is sealed by a non-referenced o-ring. FIG. 2 shows a second, more compact embodiment of the dosing module 10. For the description of this figure as well as that of the following figures, the same references for the same elements or the functionally equivalent elements of the dosing module 10 will be used. Figure 1 which will not be detailed again.

In this embodiment, the valve group 18 is an integral part of the base 14 and the flange 12. This means that there is no fastener 22 of Figure 1. For this purpose, the part The cylindrical housing 16 is a separate piece adjusted to fit the base 14 and sealingly secured by a weld seam 52. Other attachment possibilities are conceivable as those mentioned above. In this embodiment, the valve unit 18 is housed in the flange 12 and the drive unit 36 is inserted into the housing 16 starting from the side opposite that of the flange 12. FIG. 22 of the metering valve 24 of Figure 1 with a second possibility for its attachment to the flange 12 in a detail representation. The fastener 22 has a substantially conical shape towards the inside of the do-wise module 10; the fixing member 22 is fitted into the opening of the flange 12. The fixing member 22 is further blocked and sealed by the matting 56. In addition, the fixing member 22 is applied inside. of the dosing module 10 against a shoulder forming a stop 58. Figure 4 shows the housing (fastener) 22 of the metering valve 24 of Figure 1 with a third possibility of attachment to the flange 12 in a detail representation. In this case, the profiling of the fixing member 22 is used. Instead of the shoulder

8 forming an abutment 58, there is provided here a fixing by self-latching 60. By this attachment, the bead 61 is pressed into the flange 12 when it depresses the fastener 22. The fastener 22 operates and as a transformation tool that deforms the bead 61 of the flange 12. For this, the flange 12 is preferably aluminum or other material easy to deform. This connection by self-locking or automation blocks and seals the fastener 22 relative to the flange 12 in addition to the matting or crimping 56. Figure 5 shows a second embodiment of the caulk seal 46 of Figure 1 or Figure 2 according to a detail representation. In this example, the sealing cap 46 descends to the flange 12 which allows to remove the cylindrical housing 16 (according to Figures 1 and 2). The sealing cap 46 preferably made of plastic material is attached to a ring 62 of the flange 12 which projects from the flange towards the outlet port. The ring 62 has a certain clearance with respect to the sealing cap 46. Two O-rings 64 are housed in the radial peripheral grooves of the ring 62. These seals seal the sealing cap 46 with respect to the flange 12. The sealing cap 46 substantially houses the drive unit 36 and the electromagnet (not shown in FIG. 5) of the drive unit 36 is supplied with electrical power by the drive unit 36. Cold connector contact 66 and electrical connection 68 of Figure 5. On the right side, sealing cap 46 has a cooling water connection 70 providing a circulating integrated cooling water supply 72. to the sealing cap 46. The cooling water outlet does not appear. Figure 6 shows an alternative embodiment of the sealing cap 46 of Figures 1, 2 or 5 in a detail view. The cold connection contact 66 is in the form of a contact pin and the electrical connection 68 is offset from the contact pin 66. FIGS. 7, 8, 9 show a variant of FIG. other possibilities of fixing the sealing cap 46 to the flange 12 while sealing with the flange 12. The cap

The sealing ring 46 is attached to the flange 12 by the ring 62 which projects from the flange 12 in the direction opposite to the outlet orifice. Fig. 7 shows the lower edge of the sealing cap 46 having an inward projecting portion 74 which penetrates in the manner of a snap connection into a peripheral groove 76 of the flange 12. The snap connection is secured against the opening by a safety ring 78 applied from the outside against the sealing cap 46. The sealing is performed by an O-ring 64 installed above the projecting portion 74 of FIG. 5. In addition, the sealing cap 46 of FIG. 5 has a centering pin 80 integral with the sealing cap 46 and which correctly positions the drive unit 36 in the sealing cap 46. In FIG. 8, the lower edge of the sealing cap 46 has a projecting outwardly projecting portion 74 which engages in the manner of a snap connection in a circumferential groove 76 of the flange 12. The snap connection ipage is blocked on opening by a safety ring 78 applied internally against the sealing cap 46. FIG. 9 shows the fixing of the sealing cap 46 by a crimped connection 82. The electrical connector 68 is housed at the opposite end of the sealing cap 46 in a clearance 84 of the flange 12. By deforming the edge 86 made on the flange 12 with a crimping machine or by hand, the edge 86 is pressed against the sealing cap 46. The material is thus blocked and the fixing and its sealing are guaranteed. 30 NOMENCLATURE OF THE MAIN ELEMENTS

10 dosing module 12 flange 14 base 16 housing 18 valve group 19 weld seam 20 screw 22 housing 24 metering valve 26 valve element 28 valve seat 30 gearbox inlet 32 drilling 34 diaphragm 36 drive unit 38 armature 42 adapter ring 44 weld bead 46 sealing cap 48 enlarged casing area 16 50 caulking 52 weld bead 58 stop shoulder 60 self-snap fastener 61 bead 62 ring 64 o-ring 66 connector 68 electrical connection 70 d connection cooling water 72 integrated cooling water supply 74 projecting part 80 centering spindle

Claims (1)

CLAIMS 1 °) Dosing module (10) of a liquid reducing agent, in particular an aqueous solution of urea for injecting the reducing agent in the exhaust gas line of an internal combustion engine, - the module dosing device (10) comprising a housing (14, 16) surrounding a metering device (18) and a drive unit (36) actuating the metering device (18), characterized in that - the installation device (18) and the drive unit (36) are separate units installed in the housing (14, 16), at least the area of the drive unit (36) is positioned and / or locked in the housing (14, 16) by an adapter ring (42), and the dosing device (18) is sealingly connected to the housing, - the drive unit (36) is additionally closed sealed relative to the adapter ring (42) by a sealing cap (46). 2) dosing module (10) according to claim 1, characterized in that the metering device (18) and / or the adapter ring (42) are connected to the housing (14, 16) by welding and / or crimping . 3) dosing module (10) according to claim 1, characterized in that the metering device (18) and / or the sealing cap (46) are connected to the housing (14, 16) by a connection via engagement (74, 76), in particular an interlocking connection (74, 76) cooperating with a fixing ring (78). 4) dosing module (10) according to claim 3, characterized in that the clipping connection (74, 76) is by an outer or inner jack with driving surfaces (76). 5) dosing module (10) according to claim 1, characterized in that the metering device (18) and / or the sealing cap (46) are connected to the housing (14, 16). by a crimped connection (82). 6 °) dosing module (10) according to claim 1, characterized in that the metering device (18) and / or the sealing cap (46) are connected to the housing (14, 16) by a screw connection . 7 °) metering module (10) according to claim 1, characterized in that the metering device (18) and / or the sealing cap (46) are connected to the housing (14, 16) by a self-locking fastener (60). 8) dosing module (10) according to claim 1, characterized in that the metering device (18) comprises a flange (12) body to be attached to the exhaust pipe. 9) dosing module (10) according to claim 1, characterized in that the dosing module (10) is cooled by a coolant. 10 °) dosing module (10) according to claim 9, characterized in that the dosing module (10) comprises cooling agent-ment channels (32, 72), in particular in the region of the flange ( 12) and / or in the region of the sealing cap (46). 30